Human Memory Laboratory

The clinical and cognitive neuroscience research conducted in the Human Memory Lab combines neuropsychological, cognitive neuroscience, and social psychology theories and methods. In our research we draw insight from individuals with memory disorders and cognitively normal younger and older adults. 

Current lines of research include:


Revealing normal age-related changes in autobiographical memory. Much of the work in the Human Memory Lab aims to understand why, relative to younger adults, cognitively unimpaired older adults seem to think about their past (and future) in a more “semanticized” way – meaning relying on semantic details and more general or extended event descriptions (e.g. details spanning several days). In our recent work, we have used a “think aloud” paradigm (Wank, Andrews-Hanna, & Grilli, PsyArXiv) to show that older age is associated with reduced efficiency in two episodic retrieval routes that have been linked to prefrontal and medial temporal lobe recollection. In addition, we (Acevedo-Molina, Matijevic, & Grilli, 2020, Memory) showed that when asked to describe life chapters, which are broad, conceptual periods of time (e.g., first job or living in Tucson), older adults generate more detail than younger adults, suggesting that this story-telling corresponds with older adults’ retrieval style. The Human Memory Lab, along with our collaborators Dr. Jessica Andrews-Hanna and Dr. Matthias Mehl, have started to used smartphone applications to assess autobiographical memory. In one project (Wank, et al., Grilli, in press), we drew on evidence of fairly widespread age-related alterations to the default network of the brain, which has been implicated in both episodic and semantic autobiographical retrieval, to propose that reflecting on the past may become less common with advanced age – a finding that would be difficult to reveal in constrained, brief lab tasks. Using a smartphone app that records ambient sound, we showed that older age is associated with less sharing of autobiographical memories in daily conversations.

 

Uncovering early cognitive and brain markers of Alzheimer’s disease risk in autobiographical memory and the default network. In addition to characterizing normal age-related cognitive outcomes, in the Human Memory Lab, we are studying whether autobiographical memory might aid in the pre-clinical detection of Alzheimer’s disease. We have hypothesized that because autobiographical memory places a high burden on the core brain network affected by Alzheimer’s disease, namely the default network, some of the earliest signs of this age-related disease may be found in the way middle-aged and older adults reflect on their personal past. We have shown that in cognitively unimpaired older adults, we can associate declines in autobiographical memory episodic specificity, meaning episodic memory retrieval or detail generation, with advanced age (Wank et al., in press), the structural integrity of the fornix and cortical pathways vulnerable to aging and Alzheimer’s disease (Memel, Wank, Ryan, & Grilli, 2020, Cortex), and the e4 allele of the APOE gene, which increases risk for Alzheimer’s disease (Grilli et al., 2018, JINS; in prep). We, along with our collaborator Dr. Jessica Andrews-Hanna, have since extended our hypothesis to include other forms of autobiographical thought and to propose a more refined connection between autobiographical thought patterns and integrity of the default network (Andrews-Hanna et al., 2019, OREP).

 

Elucidating the role of the medial temporal lobe in autobiographical memory. A longstanding view is that there are two basic types of autobiographical memory: episodic memories, meaning memories of unique events, and personal semantics, which are facts/knowledge about the self. Until recently, far more attention was given to how these two types of autobiographical memory differed as opposed to how they might be similar. In the Human Memory Lab, we have been particularly interested in revealing how the medial temporal lobe, a brain region long implicated in episodic memories, contributes to personal semantics. Through lesion-based work, we have shown that some personal semantics depend on the medial temporal lobe for retrieval, namely knowledge that describes the scene or timing of repeated events (e.g., family dinners) and extended events (e.g., college years) (Grilli & Verfaellie, 2014; 2016, Neuropsychologia). In contrast, we have found that conceptually-based personal semantics, such as abstract facts about one’s life and one’s personality, depend on anterior lateral temporal and medial prefrontal cortical regions, which are implicated in general semantics (Grilli, Bercel, Wank, & Rapcsak, 2018; Marquine, Grilli, et al., 2016, Neuropsychologia).

 

Advancing understanding of how autobiographical memory is necessary for maintaining the self-concept. We have shown that despite profound episodic memory deficits, individuals with medial temporal lobe amnesia can turn to memory to reflect on their identity, contemplating what “defines them” and constructing the basic narrative of their life story (Grilli & Verfaellie, 2015, SCAN; Grilli & Verfaellie, 2016; Grilli, Wank, & Verfaellie, 2018; Grilli, Bercel, Wank, & Rapcsak, 2018, Neuropsychologia). Yet, whereas cognitively normal individuals tend to retrieve a rich combination of episodic and semantic memories from across the lifespan, individuals with medial temporal lobe amnesia rely on a limited set of facts, which seems to have consequences for how they describe their identity and life story. For instance, the sense of self in individuals with medial temporal lobe amnesia seems to be less robust, as these individuals tend to describe their identity with fewer traits and trait-supporting memories. The life stories of individuals with medial temporal lobe amnesia also appear to lack complexity, with less reference to themes (i.e., “chapters”) and memories that overlap in time. Our results indicate that the medial temporal lobe has a role in forming and elaborating identity, which has implications for other clinical populations

 

Investigating self-referential processing as a means for improving memory. Although much of our research has focused on advancing cognitive neuroscience models, in the Human Memory Lab we are always considering how insights from basic research can inform new interventions for memory disorders. Dr. Grilli’s first line of research merged two largely separate literatures on self-referential processing and imagination to establish a new cognitive strategy for improving episodic memory in individuals with acquired brain injury, which he and his colleagues referred to as self-imagination. We have demonstrated that self-imagination is a highly effective cognitive intervention for individuals with traumatic brain injury and cognitively normal older adults, capable of enhancing recognition, cued recall, free recall, and prospective memory across various delays and over and above a variety of cognitive strategies.